/*

Copyright (c) 2007, Arvid Norberg
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the distribution.
    * Neither the name of the author nor the names of its
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

*/

#if defined __linux__ || defined BSD
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#elif defined WIN32
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#include <iphlpapi.h>
#endif

#include "libtorrent/enum_net.hpp"
#include <asio/ip/host_name.hpp>

namespace libtorrent
{
	namespace
	{
		address sockaddr_to_address(sockaddr const* sin)
		{
			if (sin->sa_family == AF_INET)
			{
				typedef asio::ip::address_v4::bytes_type bytes_t;
				bytes_t b;
				memcpy(&b[0], &((sockaddr_in const*)sin)->sin_addr, b.size());
				return address_v4(b);
			}
			else if (sin->sa_family == AF_INET6)
			{
				typedef asio::ip::address_v6::bytes_type bytes_t;
				bytes_t b;
				memcpy(&b[0], &((sockaddr_in6 const*)sin)->sin6_addr, b.size());
				return address_v6(b);
			}
			return address();
		}
	}
	
	bool in_subnet(address const& addr, ip_interface const& iface)
	{
		if (addr.is_v4() != iface.interface_address.is_v4()) return false;
		// since netmasks seems unreliable for IPv6 interfaces
		// (MacOS X returns AF_INET addresses as bitmasks) assume
		// that any IPv6 address belongs to the subnet of any
		// interface with an IPv6 address
		if (addr.is_v6()) return true;

		return (addr.to_v4().to_ulong() & iface.netmask.to_v4().to_ulong())
			== (iface.interface_address.to_v4().to_ulong() & iface.netmask.to_v4().to_ulong());
	}

	bool in_local_network(asio::io_service& ios, address const& addr, asio::error_code& ec)
	{
		std::vector<ip_interface> const& net = enum_net_interfaces(ios, ec);
		if (ec) return false;
		for (std::vector<ip_interface>::const_iterator i = net.begin()
			, end(net.end()); i != end; ++i)
		{
			if (in_subnet(addr, *i)) return true;
		}
		return false;
	}
	
	std::vector<ip_interface> enum_net_interfaces(asio::io_service& ios, asio::error_code& ec)
	{
		std::vector<ip_interface> ret;
// covers linux, MacOS X and BSD distributions
#if defined __linux__ || (defined __APPLE__ && __MACH__) || defined __FreeBSD__ || defined __NetBSD__ \
	|| defined __OpenBSD__ || defined __bsdi__ || defined __DragonFly__
		int s = socket(AF_INET, SOCK_DGRAM, 0);
		if (s < 0)
		{
			ec = asio::error::fault;
			return ret;
		}
		ifconf ifc;
		char buf[1024];
		ifc.ifc_len = sizeof(buf);
		ifc.ifc_buf = buf;
		if (ioctl(s, SIOCGIFCONF, &ifc) < 0)
		{
			close(s);
			ec = asio::error_code(errno, asio::error::system_category);
			return ret;
		}

		char *ifr = (char*)ifc.ifc_req;
		int remaining = ifc.ifc_len;

		while (remaining)
		{
			ifreq const& item = *reinterpret_cast<ifreq*>(ifr);

			if (item.ifr_addr.sa_family == AF_INET
				|| item.ifr_addr.sa_family == AF_INET6)
			{
				ip_interface iface;
				iface.interface_address = sockaddr_to_address(&item.ifr_addr);

				ifreq netmask = item;
				if (ioctl(s, SIOCGIFNETMASK, &netmask) < 0)
				{
					if (iface.interface_address.is_v6())
					{
						// this is expected to fail (at least on MacOS X)
						iface.netmask = address_v6::any();
					}
					else
					{
						close(s);
						ec = asio::error_code(errno, asio::error::system_category);
						return ret;
					}
				}
				else
				{
					iface.netmask = sockaddr_to_address(&netmask.ifr_addr);
				}
				ret.push_back(iface);
			}

#if (defined __APPLE__ && __MACH__) || defined __FreeBSD__ || defined __NetBSD__ \
	|| defined __OpenBSD__ || defined __bsdi__ || defined __DragonFly__
			int current_size = item.ifr_addr.sa_len + IFNAMSIZ;
#elif defined __linux__
			int current_size = sizeof(ifreq);
#endif
			ifr += current_size;
			remaining -= current_size;
		}
		close(s);

#elif defined WIN32

		SOCKET s = socket(AF_INET, SOCK_DGRAM, 0);
		if (s == SOCKET_ERROR)
		{
			ec = asio::error_code(WSAGetLastError(), asio::error::system_category);
			return ret;
		}

		INTERFACE_INFO buffer[30];
		DWORD size;
	
		if (WSAIoctl(s, SIO_GET_INTERFACE_LIST, 0, 0, buffer,
			sizeof(buffer), &size, 0, 0) != 0)
		{
			ec = asio::error_code(WSAGetLastError(), asio::error::system_category);
			closesocket(s);
			return ret;
		}
		closesocket(s);

		int n = size / sizeof(INTERFACE_INFO);

		ip_interface iface;
		for (int i = 0; i < n; ++i)
		{
			iface.interface_address = sockaddr_to_address(&buffer[i].iiAddress.Address);
			iface.netmask = sockaddr_to_address(&buffer[i].iiNetmask.Address);
			if (iface.interface_address == address_v4::any()) continue;
			ret.push_back(iface);
		}

#else
#warning THIS OS IS NOT RECOGNIZED, enum_net_interfaces WILL PROBABLY NOT WORK
		// make a best guess of the interface we're using and its IP
		udp::resolver r(ios);
		udp::resolver::iterator i = r.resolve(udp::resolver::query(asio::ip::host_name(ec), "0"), ec);
		if (ec) return ret;
		ip_interface iface;
		for (;i != udp::resolver_iterator(); ++i)
		{
			iface.interface_address = i->endpoint().address();
			if (iface.interface_address.is_v4())
				iface.netmask = address_v4::netmask(iface.interface_address.to_v4());
			ret.push_back(iface);
		}
#endif
		return ret;
	}

	address router_for_interface(address const interface, asio::error_code& ec)
	{
#ifdef WIN32

		// Load Iphlpapi library
		HMODULE iphlp = LoadLibraryA("Iphlpapi.dll");
		if (!iphlp)
		{
			ec = asio::error::fault;
			return address_v4::any();
		}

		// Get GetAdaptersInfo() pointer
		typedef DWORD (WINAPI *GetAdaptersInfo_t)(PIP_ADAPTER_INFO, PULONG);
		GetAdaptersInfo_t GetAdaptersInfo = (GetAdaptersInfo_t)GetProcAddress(iphlp, "GetAdaptersInfo");
		if (!GetAdaptersInfo)
		{
			FreeLibrary(iphlp);
			ec = asio::error::fault;
			return address_v4::any();
		}

		PIP_ADAPTER_INFO adapter_info = 0;
		ULONG out_buf_size = 0;
		if (GetAdaptersInfo(adapter_info, &out_buf_size) != ERROR_BUFFER_OVERFLOW)
		{
			FreeLibrary(iphlp);
			ec = asio::error::fault;
			return address_v4::any();
		}

		adapter_info = (IP_ADAPTER_INFO*)malloc(out_buf_size);
		if (!adapter_info)
		{
			FreeLibrary(iphlp);
			ec = asio::error::fault;
			return address_v4::any();
		}

		address ret;
		if (GetAdaptersInfo(adapter_info, &out_buf_size) == NO_ERROR)
		{
			PIP_ADAPTER_INFO adapter = adapter_info;
			while (adapter != 0)
			{
				if (interface == address::from_string(adapter->IpAddressList.IpAddress.String, ec))
				{
					ret = address::from_string(adapter->GatewayList.IpAddress.String, ec);
					break;
				}
				adapter = adapter->Next;
			}
		}
   
		// Free memory
		free(adapter_info);
		FreeLibrary(iphlp);

		return ret;

#else
		// TODO: temporary implementation
		if (!interface.is_v4())
		{
			ec = asio::error::fault;
			return address_v4::any();
		}
		return address_v4((interface.to_v4().to_ulong() & 0xffffff00) | 1);
#endif
	}

}